Circular economy for plastic waste to polyethylene via oil refinery with filtering and metal oxide treatment of pyrolysis oil

ABSTRACT

Provided in one embodiment is a continuous process for converting waste plastic comprising polyethylene and/or polypropylene into recycle for polyethylene polymerization. The process comprises selecting waste plastics containing polyethylene, polypropylene, or a mixture thereof, and passing the waste plastics through a pyrolysis reactor to thermally crack at least a portion of the polyolefin waste and produce a pyrolyzed effluent. The pyrolyzed effluent is separated into offgas, a pyrolysis oil comprising a naphtha, diesel and heavy fractions, and char. The pyrolysis oil, or at least a fraction, is passed to a filtration/metal oxide treatment, with the treated product passed to a refinery FCC unit. A liquid petroleum gas C3 olefin/paraffin mixture fraction is recovered from the FCC unit, as well as a C4 olefin/paraffin mixture fraction. The liquid petroleum gas C3 olefin/paraffin mixture fraction is passed to a steam cracker for ethylene production.

The present application claims priority to U.S. Provisional PatentApplication No. 63/014,004, filed Apr. 22, 2020, the contents of whichare herein incorporated by reference in their entirety.

BACKGROUND

The world has seen extremely rapid growth of plastics production.According to PlasticsEurope Market Research Group, the world plasticsproduction was 335 million tons in 2016, 348 million tons in 2017 and359 million tons in 2018. According to McKinsey & Company, the globalplastics-waste volume was estimated about 260 million tons per year in2016, and projected to be 460 million tons per year by 2030 if thecurrent trajectory continues.

Single use plastic waste has become an increasingly importantenvironmental issue. At the moment, there appear to be few options forrecycling polyethylene and polypropylene waste plastics to value-addedchemical and fuel products. Currently, only a small amount ofpolyethylene and polypropylene is recycled via chemical recycling, whererecycled and cleaned polymer pellets are pyrolyzed in a pyrolysis unitto make fuels (naphtha, diesel), steam cracker feed or slack wax.

Processes are known which convert waste plastic into hydrocarbonlubricants. For example, U.S. Pat. No. 3,845,157 discloses cracking ofwaste or virgin polyolefins to form gaseous products such asethylene/olefin copolymers which are further processed to producesynthetic hydrocarbon lubricants. U.S. Pat. No. 4,642,401 discloses theproduction of liquid hydrocarbons by heating pulverized polyolefin wasteat temperatures of 150-500° C. and pressures of 20-300 bars (2-30 MPa).U.S. Pat. No. 5,849,964 discloses a process in which waste plasticmaterials are depolymerized into a volatile phase and a liquid phase.The volatile phase is separated into a gaseous phase and a condensate.The liquid phase, the condensate and the gaseous phase are refined intoliquid fuel components using standard refining techniques. U.S. Pat. No.6,143,940 discloses a procedure for converting waste plastics into heavywax compositions. U.S. Pat. No. 6,150,577 discloses a process ofconverting waste plastics into lubricating oils. EP0620264 discloses aprocess for producing lubricating oils from waste or virgin polyolefinsby thermally cracking the waste in a fluidized bed to form a waxyproduct, optionally using a hydrotreatment, then catalyticallyisomerizing and fractionating to recover a lubricating oil.

Other documents which relate to processes for converting waste plasticinto lubricating oils include U.S. Pat. Nos. 6,288,296; 6,774,272;6,822,126; 7,834,226; 8,088,961; 8,404,912; and 8,696,994; and U.S.Patent Publication Nos. 2019/0161683; 2016/0362609; and 2016/0264885.The foregoing patent documents are incorporated herein by reference intheir entirety.

The current method of chemical recycling via pyrolysis cannot make a bigimpact for the plastics industry. The current pyrolysis operationproduces poor quality fuel components (naphtha and diesel rangeproducts), but the quantity is small enough that these products can beblended into fuel supplies. However, this simple blending cannotcontinue if very large volumes of waste polyethylene and polypropyleneare to be recycled to address environmental issues. The products asproduced from a pyrolysis unit are of too poor quality to be blended inlarge amounts (for example 5-20 vol. % blending) in transportationfuels.

In order to achieve recycling of single use plastics in an industriallysignificant quantity to reduce its environmental impact, more robustprocesses are needed. The improved processes should establish “circulareconomy” for the waste polyethylene and polypropylene plastics where thespent waste plastics are recycled effectively back as starting materialsfor polymers and high value byproducts.

SUMMARY

Provided is a continuous process for converting waste plastic intorecycle for polyethylene polymerization. The process comprises selectingwaste plastics containing polyethylene and/or polypropylene. These wasteplastics are then passed through a pyrolysis reactor to thermally crackat least a portion of the polyolefin waste and produce a pyrolyzedeffluent. The pyrolyzed effluent is separated into offgas, a pyrolysisoil comprising naphtha, diesel and heavy fractions, and char. Pyrolysiswax can also be produced in addition to pyrolysis oil.

The incorporation of the process with an oil refinery is an importantaspect of the present process, and allows the creation of a circulareconomy with a single use waste plastic such as polyethylene orpolypropylene. Thus, the pyrolysis oil, for example, the entire liquidfraction from the pyrolysis unit, is passed to a refinery FCC unit fromwhich can be recovered liquid petroleum olefin streams. These liquidpetroleum olefin streams can be passed directly to a steam cracker forethylene production. The ethylene is then passed to a polymerizationunit for polyethylene production.

Another important aspect of the present process is the upgrading of theliquid pyrolysis product before the stream is integrated with a refineryunit. The pyrolysis oil and wax waste plastics contain contaminants thatcannot be fed in a large quantity to refinery units, such as an FCCunit, as they deactivate the refining catalysts, cause plugging in theunit or cause corrosion in processing units, which are commonly made ofcarbon steel. The use of fine filtration followed by a metal oxidetreatment has been found to be an effective treatment process to upgradethe pyrolysis products for then safely processing in refinery units. Theuse of the fine filtration and metal oxide treatment allows effectiverecycling in large volumes when integrated with a refinery.

In another embodiment, a continuous process for converting waste plasticcomprising polyethylene into recycle for polyethylene polymerization isprovided. The process comprises selecting waste plastics containingpolyethylene and/or polypropylene and then passing the waste plasticsthrough a pyrolysis reactor to thermally crack at least a portion of thepolyolefin waste and produce a pyrolyzed effluent. The pyrolyzedeffluent is separated into offgas, a pyrolysis oil comprising naphtha,diesel and heavy fractions, and char. The pyrolysis oil, the entireliquid fraction from the pyrolysis unit, is subjected to a finefiltration and then a metal oxide treatment. The resulting treatedpyrolysis product is then safely passed to a refinery FCC unit. The FCCunit will convert the treated pyrolysis oil product into FCC hydrocarbonproduct. The FCC product is sent to a FCC unit separation section toproduce offgas, C₃, C₄, FCC gasoline and heavy fractions. From theseparation section, a clean C₃ liquid petroleum gas (LPG) fractioncontaining propane and propylene is collected. The C₃ stream is a goodfeed for a steam cracker. The C₃ stream is fed to a steam crackerdistillation section to separate into propane and propylene. Then,propane is fed to the steam cracker to be converted to pure ethylene.The ethylene is then polymerized, and subsequently made intopolyethylene products.

The FCC gasoline recovered is sent to a gasoline blending pool. Theheavy portion of the hydrocarbon from the FCC unit distillation is sentto appropriate refinery units for upgrading into clean gasoline anddiesel. The C₄ LPG fraction recovered contains butanes and butenes andcan also be sent to various upgrading processes to make clean gasolineand diesel.

In one embodiment, the treated pyrolysis oil is passed to a refinery FCCFeed Pretreater Unit prior to the FCC unit. This unit is effective inremoving sulfur, nitrogen, phosphorus, silica, dienes and metals thatwill hurt a FCC unit catalyst performance. Also this unit hydrogenatesaromatics and improves the liquid yield of the FCC unit.

Among other factors, it has been found that by adding refineryoperations one can upgrade the waste pyrolysis oil and wax to highervalue products such as gasoline, diesel, and base oil. Also, by addingrefinery operations it has been found that clean naphtha (C₅-C₈) or C₄or C₃ can be efficiently and effectively produced from the wastepyrolysis oil for ultimate polyethylene polymer production. Positiveeconomics are realized for the overall process from recycled plastics toa polyethylene product with product quality identical to that of virginpolymer. It has been further discovered that a most effective process isachieved upon upgrading the pyrolysis oil prior to integration into therefinery operation. Utilizing a combination of fine filtration with ametal oxide treatment has been found most effective. Suchfiltration/metal oxide treatments of the pyrolysis oil safely allowsmuch larger volumes of waste plastic recycle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts the current practice of pyrolyzing waste plastics toproduce fuel or wax (base case).

FIG. 2 depicts a present process for filtration/metal oxide treatment ofpyrolysis oil at a pyrolysis facility.

FIG. 3 depicts a present process for establishing a circular economy forwaste plastics to recycled polyethylene in accordance with the presentprocesses including filtration/metal oxide treatment of pyrolysis oil.

FIG. 4 depicts a present process for establishing a circular economy forwaste plastics to recycled polyethylene in accordance with the presentprocesses including filtration/metal oxide treatment of pyrolysis oiloccurring in a refinery.

FIG. 5 depicts the plastic type classification for waste plasticsrecycling.

DETAILED DESCRIPTION

In the present process, provided is a method to recycle wastepolyethylene and/or polypropylene back to virgin polyethylene andestablish a circular economy by combining distinct industrial processes.A substantial portion of polyethylene and polypropylene polymers areused in single use plastics and get discarded after its use. The singleuse plastic waste has become an increasingly important environmentalissue. At the moment, there appear to be few options for recyclingpolyethylene and polypropylene waste plastics to value-added chemicalsand fuel products. Currently, only a small amount ofpolyethylene/polypropylene is recycled via chemical recycling, whererecycled and cleaned polymer pellets are pyrolyzed in a pyrolysis unitto make fuels (naphtha, diesel), steam cracker feed or slack wax.

Ethylene is the most produced petrochemical building block. Ethylene isproduced in hundreds of millions of tons per year via steam cracking.The steam crackers use either gaseous feedstocks (ethane, propane and/orbutane) or liquid feed stocks (naphtha or gas oil). It is a noncatalyticcracking process operating at very high temperatures, up to 850° C.

Polyethylene is used widely in various consumer and industrial products.Polyethylene is the most common plastic, over 100 million tonnes ofpolyethylene resins are produced annually. Its primary use is inpackaging (plastic bags, plastic films, geomembranes, containersincluding bottles, etc.). Polyethylene is produced in three main forms:high-density polyethylene (HDPE, ˜0.940-0.965 g/cm⁻³), linearlow-density polyethylene (LLDPE, ˜0.915-0.940 g/cm⁻³) and low-densitypolyethylene (LDPE, (<0.930 g/cm⁻³), with the same chemical formula(C₂H₄)_(n) but different molecular structure. HDPE has a low degree ofbranching with short side chains while LDPE has a very high degree ofbranching with long side chains. LLDPE is a substantially linear polymerwith significant numbers of short branches, commonly made bycopolymerization of ethylene with short-chain alpha-olefins.

Low density polyethylene (LDPE) is produced via radical polymerizationat 150-300° C. and very high pressure of 1,000-3,000 atm (101-304 MPa).The process uses a small amount of oxygen and/or organic peroxideinitiator to produce polymer with about 4,000-40,000 carbon atoms perthe average polymer molecule, and with many branches. High densitypolyethylene (HDPE) is manufactured at relatively low pressure (10-80atm, 1-8 MPa) and 80-150° C. temperature in the presence of a catalyst.Ziegler-Natta organometallic catalysts (titanium(III) chloride with analuminum alkyl) and Phillips-type catalysts (chromium(IV) oxide onsilica) are typically used, and the manufacturing is done via a slurryprocess using a loop reactor or via a gas phase process with a fluidizedbed reactor. Hydrogen is mixed with ethylene to control the chain lengthof the polymer. Manufacturing conditions of linear low-densitypolyethylene (LLDPE) is similar to those of HDPE except copolymerizationof ethylene with short-chain alpha-olefins (1-butene or 1-hexene).

Today, only a small portion of spent polyethylene and polypropyleneproducts are collected for recycling efforts due to the inefficienciesdiscussed above. The present process allows larger volumes of single useplastic waste to be safely recycled by using a process integrated with arefinery. A circular economy is effectively established by the presentprocess.

FIG. 1 shows a diagram of pyrolysis of waste plastics fuel or wax thatis generally operated in the industry today. As noted above, generally,polyethylene and polypropylene wastes are sorted together 1. The cleanedpolyethylene/polypropylene waste 2 is converted in a pyrolysis unit 3 tooffgas 4 and pyrolysis oil (liquid product). The offgas 4 from thepyrolysis unit is used as fuel to operate the pyrolysis unit. Adistillation unit in the pyrolysis unit separates the pyrolysis oil toproduce naphtha and diesel 5 products which are sold to fuel markets.The heavy pyrolysis oil fraction 6 is recycled back to the pyrolysisunit 3 to maximize the fuel yield. Char 7 is removed from the pyrolysisunit 3. The heavy fraction 6 is rich in long chain, linear hydrocarbons,and is very waxy (i.e., forms paraffinic wax upon cooling to ambienttemperature). Wax can be separated from the heavy fraction 6 and sold tothe wax markets.

It has been discovered that an upgrading of the pyrolysis oil prior tointroduction into refinery units improves the effectiveness and safetyof the overall process. More specifically, critical materials that needto be removed from the pyrolysis products for co-feeding to a refineryunit includes components such as residual char, metals and chlorides.Pyrolysis products with these impurities cannot be fed in large quantityto refinery units as chars and inorganic solids will cause plugging inthe unit, metals will deactivate the refining catalysts permanently andchlorides will cause corrosion in processing equipment. Reduction ofchloride impurity is particularly important prior to feeding to refineryunits as chlorides may cause severe corrosion on bare carbon steel withwhich most of refinery units are constructed. The chloride inducedcorrosion will be particularly accelerated at elevated temperaturesabove 500° F. (260° C.), where most of refinery units are operating.

The pyrolysis product treatment of the present process can be doneefficiently in conjunction with the pyrolysis unit during the pyrolysisoil and wax manufacturing. Or the treatment can be done at the refinerybefore feeding the pyrolysis oil and wax to the refinery units. Thepresent fine filtration and metal oxide treatment process does notreduce S and N impurities, nor olefin and diene contents. In the presentprocess for circular economy establishment, conversion of thesecompounds are effectively achieved by refinery units such as a fluidcatalytic cracking (FCC) unit, a FCC feed pretreater, refinery crudeunit, coker, distillate hydrotreater or hydrocracker.

The present process converts pyrolyzed polyethylene and/or polypropylenewaste plastic in large quantities by integrating the waste polymerpyrolysis product streams into an oil refinery operation. The resultingprocesses produce the feedstocks for the polymers (naphtha or C₃-C₄ orC₃ only for an ethylene cracker), high quality gasoline, jet and dieselfuel, and/or quality base oil.

Generally, the present process provides a circular economy forpolyethylene plants. Polyethylene is produced via polymerization of pureethylene. Clean ethylene can be made using a steam cracker. Eithernaphtha or a C₃ or C₄ stream can be fed to the steam cracker. Theethylene is then polymerized to create polyethylene.

By adding refinery operations to upgrade the waste pyrolysis oil tohigher value products (gasoline and diesel, base oil) and to produceclean LPG and naphtha for a steam cracker for ultimate polyethylenepolymer production, one is able to create positive economics for theoverall process from recycled plastics to polyethylene product withquality identical to that of the virgin polymer.

A pyrolysis unit produces poor quality products containing contaminants,such as calcium, magnesium, chlorides, nitrogen, sulfur, phosphorus,silicon, dienes, and heavy components, which products cannot be used inlarge quantity for blending in transportation fuels. It has beendiscovered that by having these products go through the refinery units,the contaminants can be captured in pre-treating units and theirnegative impacts diminished. The fuel components can be further upgradedwith appropriate refinery units with chemical conversion processes, withthe final transportation fuels produced by the integrated process beingof higher quality and meeting the fuels quality requirements. Thepresent process will upgrade the wax into valuable gasoline, diesel andbase oil. The integrated process will generate much cleaner naphthastream as steam cracker feedstock for ethylene generation andpolyethylene production. These large on-spec productions allow “cyclicaleconomy” for the recycle plastics feasible.

However, it has been discovered, and is an important aspect of thepresent process, that upgrading of the pyrolysis product is still neededbefore the stream is integrated with a refinery unit. The pyrolysis oiland wax waste plastics contain contaminants that cannot be fed in largequantity to refinery units as they deactivate the refining catalysts orcause plugging in the unit or cause severe corrosion in processing unitswhich are commonly made of bare carbon steel.

FIG. 2 depicts a process sequence of a fine filtration and metal oxidetreatment. In FIG. 2 , the cleaned polyethylene/polypropylene waste 22is passed through a pyrolysis reactor 23 to thermally crack at least aportion of the polyolefin waste and produce a pyrolyzed effluent. Char26 is generally removed from the pyrolysis reactor 23. The effluent ispassed through a heat exchange 60 for partial cooling and then to agas-liquid separation unit 61. Offgas 24 can be used as fuel to operatethe pyrolysis unit. The liquid product from the pyrolysis effluent isthen passed to a fine filtration unit 27-1. Optionally, any pyrolysiswax produced can also be passed to the fine filtration (and metal oxidetreatment).

The fine filtration unit removes solids in the pyrolysis oil,particularly chars created by the pyrolysis process and inorganic solidsarising from contamination. Metals are often present as inorganic solidsin the form of metal chlorides, metals or metal oxides. Thus, the finefiltration process reduces the contaminants coming from chars, metals,metal oxides and metal chlorides. A very fine filter medium needs to beused, preferentially less than 5 micron, more preferentially less than2.5 micron and most preferentially less than 1 micron nominal-ratedfilter. Multiple filter units with different size filter elements may beused in series. These filter media are well known for industrial uses.The filter media must be able to withstand the temperature of thepyrolysis oil as well as the chemical nature of especially thecontaminants. The residual solid content can be measured, for example,by the Heptane Insolubles test, ASTM D-3279 method. The content ofHeptane Insolubles needs to be reduced to less than 0.5 wt. %,preferably less than 0.1%.

After the filtration, the filtered liquid effluent is passed to metaloxide treatment 27-2. The metal oxide treatment removes organicchlorides and metals from the filtered pyrolysis oil. The chloride andimpurity removal is more effective when the metal oxide treatmenttemperature is done above 200° F. (93° C.), preferentially above 300° F.(149° C.), and most preferentially above 400° F. (204° C.). Preferredpressure range is from atmospheric pressure to 1000 psig, preferentiallyfrom 0 psig to 600 psig. To reduce fouling of metal oxide and to improvethe performance, optionally H₂ gas may be added to the treating process.The preferred amount of H₂ gas flow is ranging from 0 to 2000 scf/bbl ofpyrolysis oil. Metal oxides with high surface area can also captureadditional contaminants. Metal oxides such as Cao, ZnO, MgO, alumina,silica, clay, and silica-alumina are effective for chloride removal.Mixed metal oxides made of Mg, Ca, Al or Zn, or combination of these areparticularly effective for organic chloride removal. It is desirable toreduce the chloride content to less than 10 ppm, preferably less than 5ppm and most preferably less than 1 ppm. Metal oxides made of Ni, Mo,phosphate, alumina, silica and silica-alumina or combination of theseare particularly effective for residual metals removal while they canalso remove other contaminants such as chlorides, nitrogen, phosphorusand silicon. It is desirable to reduce the total residual metals contentto less than 10 ppm, preferably less than 5 ppm. Combination ofdifferent metal oxides can be used for effective removal of impurities.

The treated effluent can then be cooled in heat exchanger 62, with theentire treated, liquid product (naphtha, distillate and heavy fraction)25 then passed on to refinery unit 63.

FIG. 3 and FIG. 4 show the present integrated process, the filtering andmetal oxide treatment, and the integrating of refinery operations withrecycle for effective polyethylene production. The same numbers in FIG.2 , FIG. 3 , and FIG. 4 refer to the same type of units and productstreams. In FIG. 3 and FIG. 4 , mixed waste plastics are sorted together21. The cleaned waste plastic 22 is converted in a pyrolysis unit 23 tooffgas 24 and a pyrolysis oil (liquid product), and at times a wax(solid product at ambient temperature). The offgas 24 from the pyrolysisunit can be used as fuel to operate the pyrolysis unit 23. The pyrolysisoil, the entire liquid product 25, comprises the naphtha/dieseldistillate/heavy fractions. Char 26 is removed from the pyrolysis unit23 after completion of the pyrolysis step.

The pyrolysis unit can be located near the waste plastics collectionsite, which site could be away from a refinery, near a refinery, orwithin a refinery. If the pyrolysis unit is located away from therefinery, then pyrolysis oil (naphtha/diesel and heavies) can betransferred to the refinery by truck, barge, rail car or pipeline. It ispreferred, however, that the pyrolysis unit is within the waste plasticscollection site or within the refinery.

In FIG. 3 , a fine filtration and metal oxide treatment 27 is effectedat the pyrolysis facility. The whole liquid pyrolysis product 25 fromthe pyrolysis unit 23 is sent to the filtration unit followed by anoxide treatment. It is preferred that the hot pyrolysis liquid isfiltered and treated with the metal oxide before it is completely cooledto ambient temperature for storage and/or transfer. Thus, it ispreferred for the filtration and metal oxide treatment to occur at thepyrolysis facility after the whole liquid product 25 is recovered, or tooccur simultaneously with the whole liquid product collection step. Thetreated liquid product can then be transferred to the refinery.

In FIG. 4 , in another embodiment, the whole liquid product 25 istransferred to a refinery. The fine filtration and metal oxide treatment27 is completed at the refinery.

The preferred starting material for the present process is sorted wasteplastics containing predominantly polyethylene and polypropylene(plastics recycle classification types 2, 4, and 5). The pre-sortedwaste plastics are washed and shredded or pelleted to feed to apyrolysis unit for thermal cracking. FIG. 5 depicts the plastic typeclassification for waste plastics recycling. Classification types 2, 4,and 5 are high density polyethylene, low density polyethylene andpolypropylene, respectively. Any combination of the polyethylene andpolypropylene waste plastics can be used. For the present process, atleast some polyethylene waste plastic is preferred.

Proper sorting of waste plastics is very important in order to minimizecontaminants such as N, Cl, and S. Plastics waste containingpolyethylene terephthalate (plastics recycle classification type 1),polyvinyl chloride (plastics recycle classification type 3) and otherpolymers (plastics recycle classification type 7) need to be sorted outto less than 5%, preferably less than 1% and most preferably less than0.1%. The present process can tolerate a moderate amount of polystyrene(plastics recycle classification type 6). Waste polystyrene needs to besorted out to less than 30%, preferably less than 20% and mostpreferably less than 5%.

Washing of waste plastics removes metal contaminants such as sodium,calcium, magnesium, aluminum, and non-metal contaminants coming fromother waste sources. Non-metal contaminants include contaminants comingfrom the Periodic Table Group IVA, such as silica, contaminants fromGroup VA, such as phosphorus and nitrogen compounds, contaminants fromGroup VIA, such as sulfur compounds, and halide contaminants from GroupVIIA, such as fluoride, chloride, and iodide. The residual metals,non-metal contaminants, and halides need to be removed to less than 50ppm, preferentially less than 30 ppm and most preferentially to lessthan 5 ppm.

The pyrolyzing is carried out by contacting a plastic material feedstockin a pyrolysis zone at pyrolysis conditions, where at least a portion ofthe feed(s) is cracked, thus forming a pyrolysis zone effluentcomprising primarily 1-olefins and n-paraffins. Pyrolysis conditionsinclude a temperature of from about 400° C. to about 700° C., preferablyfrom about 450° C. to about 650° C. Conventional pyrolysis technologyteaches operating conditions of above-atmospheric pressures. See e.g.,U.S. Pat. No. 4,642,401. Additionally, it has been discovered that byadjusting the pressure downward, the yield of a desired product can becontrolled. See, e.g., U.S. Pat. No. 6,150,577. Accordingly, in someembodiments where such control is desired, the pyrolysis pressure issub-atmospheric.

It has been discovered that the use of the fine filtration, e.g., 5.0micron or less pore size filter, preferably 1.0 micron or less, and inone embodiment 0.5 micron, followed by the metal oxide treatment isquite beneficial to achieving a feed stream that can be passedefficiently through a refinery without causing problems such ascorrosion, plugging or deactivation of catalysts. The treatment therebyallows larger amounts of the waste plastic pyrolysis liquid product tobe passed through the refinery for a most effective recycling process.

FIG. 3 shows the present integrated process where the entire pyrolysisoil (naphtha, distillate and heavy fractions) after filtering and metaloxide treatment 27, is sent to a fluid catalytic cracking (FCC) unit 28.Optionally, only a portion of pyrolysis oil (the distillate and heavyfractions only or the heavy fraction only) can be sent to the FCC unit.In FIG. 3 , the filtering and metal oxide treatment 27 occurs at thepyrolysis facility.

The fluid catalytic cracking (FCC) process is widely used in therefining industry for conversion of atmospheric gas oil, vacuum gas oil,atmospheric residues and heavy stocks recovered from other refineryoperations into high-octane gasoline, light fuel oil, heavy fuel oil,olefin-rich light gas (LPG) and coke. FCC uses a high activity zeolitecatalyst to crack the heavy hydrocarbon molecules at a 950-990° F.(510-532° C.) reactor temperature in a riser with a short contact timeof a few minutes or less. LPG streams containing olefins (propylene,butylene) are commonly upgraded to make alkylate gasoline, or to be usedin chemicals manufacturing. A conventional FCC unit is used.

Cracking of the pyrolysis liquid oil combined with petroleum derived oilin the FCC unit produces liquefied petroleum gas (LPG) olefin streams 31and 32, as well as a gasoline 29 and heavy fraction 30. A C₂ ⁻ offgas 33is also produced.

The refinery will generally have its own hydrocarbon feed from petroleumderived oil flowing through the refinery units. The flow volume ofpyrolysis oil generated from the pyrolysis of waste plastic to therefinery units can comprise any practical or accommodating volume % ofthe total flow to the refinery units. Generally, the flow of thepyrolysis oil (and wax) generated from the waste plastic pyrolysis, forpractical reasons, can be up to about 50 vol. % of the total flow, i.e.,the refinery flow and the pyrolysis flow. In one embodiment, the flow ofthe pyrolysis oil is an amount up to about 20 vol. % of the total flow.In another embodiment, the flow of the pyrolysis oil is an amount up toabout 10 vol. % of the total flow. About 20 vol. % has been found to bean amount that is quite practical in its impact on the refinery whilealso providing excellent results and being an amount that can beaccommodated. The amount of pyrolysis oil and wax generated from thepyrolysis can of course be controlled so that the fraction passed to therefinery units provide the desired volume % of the flow.

The LPG olefin stream 31 is a C₃ liquid petroleum gas (LPG) fractioncontaining propane and propylene. This C₃ stream is a good feed for asteam cracker. The C₃ stream 31 is fed to a steam cracker 34. The C₃stream can also be fed to a steam cracker distillation section toseparate into propane and propylene. In the steam cracker 34, thepropane stream is converted to pure ethylene which is then polymerized40. The polyethylene can then be used to produce polyethylene products41.

The FCC gasoline 29 can be sent to a gasoline blending pool. The heavyportion 30 recovered from the FCC unit 28 is sent to appropriaterefinery units 38 (such as hydrotreating, hydrocracking and/or cokerunits) for upgrading into clean gasoline and diesel 39. The C₄ stream 32is either sent to a gasoline blending pool or further upgraded (viaprocesses such as alkylation or C₄ olefin dimerization or ethersynthesis) into clean gasoline.

In another embodiment, the treated pyrolysis oil is first sent to an FCCfeed pretreater (not shown) before the FCC unit. The FCC feed pretreatertypically uses a bimetallic (NiMo or CoMo) alumina catalyst in a fixedbed reactor to hydrogenate the feed with H₂ gas flow at a 660-780° F.(349-415° C.) reactor temperature and 1,000-2,000 psi (6.89-13.79 MPa)pressure. The refinery FCC feed pretreater unit is effective in removingsulfur, nitrogen, phosphorus, silica, dienes and metals that will hurtthe FCC unit catalyst performance. Also this unit hydrogenates aromaticsand improves the liquid yield of the FCC unit.

FIG. 4 shows the present integrated process where the entire pyrolysisoil (naphtha, distillate and heavy fractions) is sent to a fluidcatalytic cracking (FCC) unit 28. Optionally, only a portion ofpyrolysis oil (the distillate and heavy fractions only or the heavyfraction only) can be sent to the FCC unit. Prior to being sent to theFCC unit, the pyrolysis oil is fine filtered and subjected to a metaloxide treatment 27. In FIG. 4 , the filtering and metal oxide treatmentoccur in the refinery. The pyrolysis oil 25 is transferred to therefinery for treatment 27.

Similar to FIG. 3 , cracking of the treated pyrolysis liquid oilcombined with petroleum derived oil in the FCC unit produces liquefiedpetroleum gas (LPG) olefin streams 31 and 32, as well as a gasoline 29and heavy fraction 30. A C₂ ⁻ offgas 33 is also produced.

The LPG olefin stream 31 is a C₃ liquid petroleum gas (LPG) fractioncontaining propane and propylene. This C₃ stream is a good feed for asteam cracker. The C₃ stream 31 is fed to a steam cracker 34. In thesteam cracker 34, the C₃ stream is converted to pure ethylene which isthen polymerized 40. The polyethylene can then be used to producepolyethylene products 41.

The LPG olefin stream 32 is a C₄ liquid petroleum gas (LPG) fractioncontaining butanes and butenes. This fraction can be sent to a refineryalkylation unit 35 (not shown).

The FCC gasoline 29 can be sent to a gasoline blending pool. The heavyportion 30 recovered from the FCC unit 28 is sent to appropriaterefinery units 38 for upgrading into clean gasoline and diesel 39.

In another embodiment, the treated pyrolysis oil is first sent to an FCCfeed pretreater (not shown). The FCC feed pretreater typically uses abimetallic (NiMo or CoMo) alumina catalyst in a fixed bed reactor tohydrogenate the feed with H2 gas flow at a 660-780° F. (349-415° C.)reactor temperature and 1,000-2,000 (6.89-13.79 MPa) psi pressure. Therefinery FCC feed pretreater unit is effective in removing sulfur,nitrogen, phosphorus, silica, dienes and metals that will hurt the FCCunit catalyst performance. Also this unit hydrogenates aromatics andimproves the liquid yield of the FCC unit.

Alternatively, instead of sending the C₃ olefin/paraffin mix 31,recovered from the FCC unit, directly to the steam cracker 34, the C₃olefin/paraffin mix stream 31 is directed to a propane/propylene (PP)splitter which is a high efficiency distillation column. A pure propanestream is recovered from the propane/propylene splitter. The purepropane fraction is then passed to the steam cracker 34 for ethyleneproduction. The propylene may be separately polymerized and made intopolypropylene consumer products.

The ethylene polymerization unit is preferably located near the refineryso that the feedstocks (propane, butane, naphtha) can be transferred viapipeline. For a petrochemical plant located away from the refinery, thefeedstock can be delivered via truck, barge, rail car, or pipeline.

The carbon in and out of the refinery operations are “transparent,”meaning that all the molecules from the waste plastic do not necessarilyend up in the exact olefin product cycled back to the polyolefin plants,but are nevertheless assumed as “credit” as the net “green” carbon inand out of the refinery is positive. With these integrated processes,the amount of virgin feeds needed for polyethylene plants will bereduced substantially.

The benefits of a circular economy and an effective and efficientrecycling campaign are realized by the present integrated process. Theuse of the fine filtering and metal oxide treatment permits largervolumes of feed to be circulated safely and efficiently through therefinery.

The following non-limiting examples are illustrative of the presentprocess and its benefits.

Example 1 Properties of Pyrolysis Oil and Wax From Commercial Sources

Pyrolysis oil and wax samples were obtained from commercial sources andtheir properties are summarized in Table 1. These pyrolysis samples wereprepared from waste plastics containing mostly polyethylene andpolypropylene via thermal decomposition in a pyrolysis reactor at around400-600° C., near atmospheric pressure without any added gas or acatalyst. A pyrolysis unit typically produces gas, liquid oil product,optionally wax product, and char. The pyrolysis unit's overhead gasstream containing thermally cracked hydrocarbon was cooled to collectcondensate as pyrolysis oil (liquid at ambient temperature) and/orpyrolysis wax (solid at ambient temperature). The pyrolysis oil is themain product of the pyrolysis units. Some units produce pyrolysis wax asa separate product in addition to the pyrolysis oil.

TABLE 1 Properties of As-Received Oil and Wax from Pyrolysis of WastePlastics Pyrolysis Oil Pyrolysis Oil Pyrolysis Oil Pyrolysis OilPyrolysis Wax Sample A Sample B Sample C Sample D Sample E SpecificGravity at 60° F. 0.814 0.820 0.774 — 0.828 Simulated Distillation, ° F.0.5% (Initial Boiling Point) 87 299 18 86 325    5% 179 306 129 154 475  10% 214 309 156 210 545   30% 322 346 285 304 656   50% 421 447 392421 733   70% 545 585 517 532 798   90% 696 798 663 676 894   95% 772883 735 743 939 99.5% (Final Boiling Point) 942 1079 951 888 1064Carlo-Erba Hydrocarbon Analysis Carbon, wt % 87.6 84.21 85.46 85.9785.94 Hydrogen, wt % 12.7 12.25 14.1 14.0 14.15 Sum of C + H, wt % 100.396.46 99.5 100.0 100.1 H/C Molar Ratio 1.73 1.75 1.98 1.96 1.98 BromineNumber, g/100 g 49 60 40 44 14 Hydrocarbon Type Total Aromatics, vol %23.3 22.8 5.1 8.7 13.3 Total Olefins & Naphthenes, vol % 39.0 50.2 42.438.2 42.1 Total Paraffins, vol % 37.7 27 52.5 53.1 44.6 ContaminantsTotal S, ppm 48 29 7.8 99 6.3 Total N, ppm 751 1410 318 353 237 TotalCl, ppm (by CIC) 113 62 41 70 4.7 Total O, ppm 250 — 574 — — TraceElemental Impurities Al, ppm <1.1 <0.56 0.6 <0.53 <0.68 Ca, ppm 1.4 11.5<0.5 <0.53 <0.68 Fe, ppm 4.9 11.9 1.6 <1.1 3.1 Mg, ppm <0.51 1.3 <0.52<0.53 <0.68 Na, ppm 2.5 <0.54 <1.1 <2.2 <2.7 Ni, ppm <0.51 <0.54 <0.52 2<0.68 V, ppm <0.51 <0.54 <0.52 4 <0.68 P, ppm 8.2 9.9 <1.6 <2.2 20.2 Si,ppm 82.5 49.6 13 17 3.1

ASTM D4052 method was used for specific gravity measurements. Simulatedboiling point distribution curve was obtained using ASTM D2887 method.Carlo-Erba analysis for carbon and hydrogen was based on ASTM D5291method. Bromine number measurement was based on ASTM D1159 method.Hydrocarbon-type analysis was done using a high resolution magnetic massspectrometer using the magnet scanned from 40 to 500 Daltons. Totalsulfur was determined using XRF per ASTM D2622 method. The nitrogen wasdetermined using a modified ASTM D5762 method using chemiluminescencedetection. The total chloride content was measured typically usingcombustion ion chromatography (CIC) instrument using modified ASTM 7359method. The oxygen content in naphtha and distillate boiling range wasestimated using GC by GC/MS measurements with electron ionizationdetector for m/Z range of 29-500. Trace metal and non-metal elements inoil were determined using inductively coupled plasma-atomic emissionspectrometry (ICP-AES).

Industrial pyrolysis process of sorted plastics, sourced predominantlyfrom polyethylene and polypropylene waste, produced quality hydrocarbonstreams with specific gravity ranging 0.7 to 0.9, and a boiling rangefrom 18 to 1100° F. as in pyrolysis oil or pyrolysis wax.

The pyrolysis product is rather pure hydrocarbon made of mostly carbonand hydrogen. The hydrogen to carbon molar ratio varies from 1.7 to near2.0. The Bromine Number is in the range of 14 through 60 indicatingvarying degrees of unsaturation coming from olefins and aromatics. Thearomatic content is in the range of 5 to 23 volume % with a higherseverity unit producing more aromatics. Depending on the processconditions of the pyrolysis unit, the pyrolysis products show paraffiniccontent ranging from mid-20 vol. % to mid-50 vol. %. The pyrolysisproduct contains a substantial amount of olefins. Samples A and B,pyrolysis oil produced under more severe conditions such as higherpyrolysis temperature and/or longer residence time, contain higheraromatic and lower paraffinic components, resulting H/C molar ratio ofaround 1.7 and high Bromine Number of 50-60. Samples C and D wereproduced at less severe conditions, and the pyrolysis oils are moreparaffinic, resulting H/C molar ratio of close to 2.0 and Bromine Numberaround 40. Sample E, pyrolysis wax, is mostly paraffinic, saturatedhydrocarbon with a substantial amount of normal hydrocarbons (as opposedto branched hydrocarbons) with low Bromine Number of only 14.

Example 2 Contaminants in Pyrolysis Oils and Micro Filtration to RemoveSolids

Pyrolysis oils or wax products contain residual solids and otherimpurities that could negatively affect the performance of conversionunits in a refinery. As received pyrolysis oil samples were vacuumfiltered through 0.7 micron glass fiber filter paper to remove residualsolids and the results are summarized in Table 2.

The residual solid content can be measured by the Heptane Insolublestest, ASTM D-3279 method. For chloride analysis, X-ray fluorescence(XRF) method was used.

TABLE 2 Impurity Removal of Pyrolysis Oil by Filtration As-Received FeedPretreating % Reduction Pyrolysis Filtration with of Impurities Oil Feed0.7 Micron Filter by Filtration Example 2-1 Heptane Insoluble Solids,ppm 1200 57 95% Contaminants Cl, ppm 67 8.4 93% Example 2-2 HeptaneInsoluble Solids, ppm 3000 61 98% Contaminants Cl, ppm 125 8.5 93%Example 2-3 Heptane Insoluble Solids, ppm 2400 33 99% Contaminants Cl,ppm 235 8.2 97% Example 2-4 Contaminants Cl, ppm 2173 1375 37% Example2-5 Contaminants Cl, ppm 9.1 10.4  0%

In the study, it was found that the pore size of the filter is importantfor impurity removal. When a 25 micron filter was used, the filter paperwas plugged and the filtration of the three pyrolysis oils could not becompleted. With a 0.7 micron filter, the filtration reduced the contentof heptane insoluble solids by 90% or higher. The study indicatedfiltration with small pore size filter, for example 1.0 micron or less,such as the 0.7 micron filter used, is effective in removing residualsolids. Surprisingly, the filtration also removed chloride impuritieseffectively (Examples 2-1 through 2-4), except one case (Example 2-5).The data suggests that a pyrolysis oil product contains varying amountsof inorganic chloride species and filtration can reduce the impuritylevel substantially. In Example 2-5, however, no reduction of chloridespecies was observed. This suggests that some chloride species areorganic in nature and further treatment would be needed beyond thefiltration process.

Example 3 Pyrolysis Oil Pretreating by Filtration Followed byCaO/ZnO/Clay Metal Oxide Treatment

As-received pyrolysis oil, Sample F, was filtered through a continuousfiltration unit containing 0.5 micron nominal filter cartridge toprepare a filtered oil, Sample F-1. The samples were analyzed forgeneral feedstock properties and impurities, as shown in Table 3.

TABLE 3 Impurity Removal of Pyrolysis Oil by Continuous Filtration FeedPre-Treating Pyrolysis Oil Pyrolysis Oil Sample F Sample F-1 % ReductionAs-Received Filtration with 0.5 of Impurities Pyrolysis Oil micronnominal filter by Filtration Heptane Insoluble Solids, ppm ~2400 314 87%Contaminants Total S, ppm 67 — — Total N, ppm 212 165 22% Total Cl, ppm2317 1848 20% Trace Elemental Impurities Fe, ppm 17.6 9.3 47% P, ppm 4.63.6 22% Si, ppm 36.4 24.4 33% Specific Gravity at 60° F. 0.7866 0.7857 —Bromine Number, g/100 g — 67 — Simulated Distillation, ° F. 0.5%(Initial Boiling Point) — 22 —   5% — 148 —  10% — 180 —  30% — 294 — 50% — 401 —  70% — 518 —  90% — 664 —  95% — 735 —  99% (Final BoilingPoint) — 859 —

The continuous filtration unit with 0.5 micron nominal filter cartridgewas effective and reduced the content of heptane insoluble solids by 87%to produce the filtered oil, Sample F-1, with 314 residual heptaneinsoluble solids. The filtration also removed a substantial amount ofother impurities such as nitrogen, chloride, iron, phosphorus andsilicon.

Sample F-1 was further treated by passing it through a fixed bed reactorcontaining metal oxide adsorbent made of CaO/ZnO/Clay. The metal oxidetreating experiments were carried out at 600 psig reactor pressure and 1LHSV flow, with the temperature varying from 200 to 400° F. 1500 SCF/BBLof hydrogen was fed to the reactor with the oil. The results aresummarized below in Table 4.

TABLE 4 Treating of Pyrolysis Oil Feed (Sample F-1) with CaO/ZnO/ClayMetal Oxide for Impurity Removal Example No. Example Example ExampleExample 4-1 4-2 4-3 4-4 Base Case Metal Oxide Treating Temperature, F.Feed Pretreating No treating 200 300 400 Impurities in Pyrolysis Oil,ppm N, ppm 165 98 106 99 Cl, ppm 1848 742 487 288 Fe, ppm 9.3 2.2 1.7<1.1 P, ppm 3.6 <3 3.1 3.3 Si, ppm 24.4 23.4 23.7 19.9 % Reduction ofImpurities by Metal Oxide Treating N, % Base case 41% 36% 40% Cl, % Basecase 60% 74% 84% Fe, % Base case 76% 82% >88%  P, % Base case ~20%  14% 8% Si, % Base case  4%  3% 18%

The metal oxide treatment step removed a substantial amount of metal(Fe) and other non-metals (N, Cl, P, Si) that could negatively affectthe performance of conversion units in a refinery. CaO and ZnOcontaining metal oxides were particularly effective for chloride andiron removal. The removal became more efficient at a higher temperature.

Example 4 Pyrolysis Oil Pretreating by Filtration Followed byNiO/MoO₃/PO₄/Alumina Metal Oxide Treatment

As-received pyrolysis oil, Sample G, was filtered through a continuousfiltration unit containing 0.5 micron nominal filter cartridge toprepare a filtered oil, Sample G-1. The samples were analyzed forgeneral feedstock properties and impurities, as shown in Table 5.

TABLE 5 Impurity Removal of Pyrolysis Oil by Continuous Filtration FeedPre-Treating Pyrolysis Oil Pyrolysis Oil Sample G Sample G-1 % ReductionAs-Received Filtration with 0.5 of Impurities Pyrolysis Oil micronnominal filter by Filtration Contaminants Total S, ppm 66 65  2% TotalN, ppm 1490 1320 11% Total Cl, ppm 533 57 89% Trace Elemental ImpuritiesCa, ppm 58.1 4.9 92% Cr, ppm 9.1 7.8 14% Fe, ppm 29.0 13.8 52% Mg, ppm2.9 0.7 75% P, ppm 18.0 18.1 −1% Si, ppm 25.8 21.5 17% Specific Gravityat 60° F. — 0.8481 — Bromine Number, g/100 g — 36 — SimulatedDistillation, ° F. 0.5% (Initial Boiling Point) — 324 —   5% — 473 — 10% — 531 —  30% — 625 —  50% — 691 —  70% — 766 —  90% — 936 —  95% —1029 —  99% (Final Boiling Point) — 1161 —

The data in Table 5 show that the continuous filtration unit with 0.5micron nominal filter cartridge was effective in reducing impuritiessuch as nitrogen, chloride, calcium, chrome, iron, magnesium andsilicon. However, the filtration did not remove any sulfur andphosphorus impurities.

Sample G-1 was further treated by passing it through a fixed bed reactorcontaining metal oxide adsorbent made of NiO/MoO₃/PO₄/Alumina. The metaloxide treating experiments were carried out at 400 psig reactor pressureand 1 LHSV flow, with the temperature varying from 500 to 550° F. 1500SCF/BBL of hydrogen was fed to the reactor with the oil. The results aresummarized below in Table 6.

TABLE 6 Treating of Pyrolysis Oil (Sample G-1) with NiO/MoO₃/PO₄/AluminaMetal Oxide for Impurity Removal Example No. Example Example Example 4-14-2 4-3 Base Case Metal Oxide Treating Temperature, ° F. FeedPretreating No treating 500 550 Bromine Number, 36 33 31 g/100 gImpurities in Pyrolysis Oil, ppm N, ppm 1320 1090 1050 Cl, ppm 57 5.1 <5Ca, ppm 4.9 <0.51 <0.52 Cr, ppm 7.8 2.1 0.75 Fe, ppm 13.8 5.4 5.4 Mg,ppm 0.7 <0.51 <0.52 P, ppm 18.1 15.7 15.4 Si, ppm 21.5 16.0 14.2 %Reduction of Impurities by Metal Oxide Treating N, % Base case 17% 20%Cl, % Base case 91% >90%  Ca, % Base case >90%  >90%  Cr, % Base case74% 90% Fe, % Base case 61% 61% Mg, % Base case >30%  >30%  P, % Basecase 13% 15% Si, % Base case 26% 34%

The metal oxide treatment step removed a substantial amount of metals(Fe, Ca, Cr, Mg) and other non-metals (N, Cl, P, Si) that couldnegatively affect the performance of conversion units in a refinery.MoO₃ and NiO containing metal oxides were particularly effective formetals removal at about 500-550° F.

The following Examples 5 through 8 show the evaluation of waste plasticspyrolysis oil for transportation fuel.

Example 5 Fractionation of Pyrolysis Oil for Evaluation asTransportation Fuel

Sample D was distilled to produce hydrocarbon cuts representing gasoline(350° F.⁻), jet (350-572° F.), diesel (572-700° F.) and the heavy (700°F.⁺) fractions. Table 7 summarizes the boiling point distribution andimpurity distributions among the distilled product fractions.

TABLE 7 Distillation of Pyrolysis Oil into Fuel Fractions Sample IDSample D Sample H Sample I Sample J Sample K Intended Fraction GasolineCut Jet Cut Diesel Cut Unconverted Cut Point Target, ° F.  350⁻ 350-572572-700  700⁺ Distillation Actual Yields,   37.2 38.0 15.0    9.3 wt %Simulated Distillation, F. IBP (0.5 wt %) 86  27 299 539 640  5 wt % 154 98 345 557 684 10 wt % 210 147 365 574 696 30 wt % 304 222 416 597 72750 wt % 421 270 457 619 758 70 wt % 532 291 492 644 808 90 wt % 676 337546 674 898 95 wt % 743 347 554 683 953 FBP (99.5 wt %) 888 385 591 7111140  Total S, ppm 99  52 35 80 320 Total N, ppm 353 215 556 232 467Total Cl, ppm 70 181 27 12  13

Example 6 Evaluation of Pyrolysis Oil Cut for Gasoline Fuel

Sample H, a pyrolysis oil cut for gasoline fuel boiling range, wasevaluated to assess its potential for use as a gasoline fuel. Sample Hhas the carbon number range of C5-C12, typical of a gasoline fuel.

Due to the olefinic nature of the pyrolysis oil, oxidation stability(ASTM D525) and gum forming tendency (ASTM D381) were identified as themost critical properties to examine. Research octane number (RON) andmotor octane number (MON) are also the critical properties for engineperformance. The RON and MON values were estimated from detailedhydrocarbon GC analysis.

TABLE 8 Evaluation of Pyrolysis Oil Naphtha Fraction for Gasoline FuelOxidation Washed Stability, Gum, mg/ min 100 mL RON MON Sample H 90 5.071.4 67.7 Reference gasoline >1440 1 95.8 86.2 4/96 vol. % Blend ofSample >1440 2.0 94.5 85.1 H with reference gasoline 15/85 vol. % Blendof Sample >1440 2.2 91.8 83.1 H with reference gasoline

Sample H, a pyrolysis oil cut for gasoline fuel boiling range, cannot beused by itself as automotive gasoline fuel due to its poor quality. Thegasoline fraction from the pyrolysis oil showed very poor oxidationstability in that Sample H failed only after 90 min compared to thetarget stability of longer than 1440 minutes. The pyrolysis gasolineexceeded the wash gum target of 4 mg/100 mL suggesting severe gumforming tendency. The pyrolysis gasoline has poor octane numberscompared to the reference gasoline. A premium unleaded gasoline was usedas the reference gasoline.

The potential of blending the pyrolysis gasoline cut in a limited amountwith the reference gasoline was also examined. The study showed thatpossibly up to 15 volume % of Sample H can be blended with the refinerygasoline while still meeting the fuels property targets. By integratingthe pyrolysis gasoline product with a refinery fuel, the overall productquality can be maintained.

These results indicate that the as-produced gasoline fraction ofpyrolysis oil has limited utility as gasoline fuel. Upgrading in arefinery unit is needed to convert the gasoline fraction of thepyrolysis oil into a hydrocarbon that meets the gasoline fuel propertytargets.

Example 7 Evaluation of Pyrolysis Oil Cut for Jet Fuel

Sample I, a pyrolysis oil cut for jet fuel boiling range, was evaluatedto assess its potential for use as jet fuel. Sample I has the carbonnumber range of C9-C18, typical of the jet fuel.

Due to the olefinic nature of the pyrolysis oil, jet fuel thermaloxidation test (D3241) was considered as an important test. Thepyrolysis oil jet cut as-is, Sample I, had only 36 minutes of oxidationstability, suggesting that the pure pyrolysis jet cut is unsuitable foruse as jet fuel.

A 5 volume % blend of pyrolysis jet cut (Sample I) with refineryproduced jet was prepared. The blend still failed the jet fuel oxidationtest as shown in Table 9.

TABLE 9 Evaluation of Pyrolysis Oil Jet Fraction for Jet Fuel Jet FuelThermal Oxidation Test Reference jet fuel Passed 5/95 vol. % Blend ofSample I Failed with reference jet fuel

These results indicate that the as-produced jet fraction of pyrolysisoil is completely unsuitable for jet fuel, and upgrading in a refineryunit is required to convert this jet fraction of the pyrolysis oil intoa hydrocarbon that meets the jet fuel property targets.

Example 8 Evaluation of Pyrolysis Oil Cut for Diesel Fuel

Sample J, a pyrolysis oil cut for diesel fuel boiling range, wasevaluated to assess its potential for use as diesel fuel. Sample J hasthe carbon number range of C14-C24, typical of a diesel fuel.

Sample J contains a substantial amount of normal hydrocarbons. Sincenormal hydrocarbons tend to exhibit waxy characteristics, cold flowproperties such as pour point (ASTM D5950-14) and cloud points (ASTMD5773) were considered as the most critical tests.

Two blends were prepared at 10 and 20 volume % of Sample J with refineryproduced diesel fuel. However, both blends still failed the target pourpoint of less than −17.8° C. (0° F.) pour points.

TABLE 10 Evaluation of Pyrolysis Oil Diesel Fraction for Diesel FuelCloud Point Pour Point Pour Point (° C.) (° C.) Test Reference dieselfuel −17.1 −19.0 Passed 10/90 vol. % Blend of Sample J −11.1 −12.0Failed with reference diesel fuel 20/80 vol. % Blend of Sample J −5.5−7.0 Failed with reference diesel fuel

These results indicate that the pyrolysis oil as-is is completelyunsuitable for diesel fuel, and upgrading in a refinery unit is requiredto covert the diesel fraction of pyrolysis oil into hydrocarbon thatmeets the diesel fuel property targets.

Example 9 Coprocessing of Pyrolysis Product to FCC Unit

By feeding the entire pyrolysis feedstock to a FCC unit after the feedpretreating as shown in FIG. 3 , the pyrolysis oil and wax are convertedinto offgas, LPG paraffins and olefins, FCC gasoline and heavyhydrocarbon components. The FCC gasoline is a valuable gasoline blendingcomponent. The heavy fractions, light cycle oil (LCO) and heavy cycleoil (HCO) are converted further in the subsequent conversion unitsincluding jet hydrotreating unit, diesel hydrotreating unit,hydrocracking unit and/or coker unit to make more gasoline, jet, anddiesel fuel with satisfactory product properties. The LPG paraffins andolefins can be either processed further in an alkylation unit or in partused for petrochemicals production with a recycle content.

The following Examples 10 and 11 demonstrate the conversion of wasteplastics pyrolysis product into quality transportation fuel in arefinery conversion unit, using a FCC unit as an example.

Example 10 Conversion of Pyrolysis Oil in FCC

To study the impact of coprocessing of waste plastics pyrolysis oil in aFCC, a series of laboratory tests were carried out with Samples A and C.Vacuum gas oil (VGO) is the typical feed for FCC. FCC performances of 20volume % blend of pyrolysis oil with VGO and pure pyrolysis oil werecompared with that of the pure VGO feed.

The FCC experiments were carried out on a Model C ACE (advanced crackingevaluation) unit fabricated by Kayser Technology Inc. using regeneratedequilibrium catalyst (Ecat) from a refinery. The reactor was a fixedfluidized reactor using N₂ as a fluidization gas. Catalytic crackingexperiments were carried out at the atmospheric pressure and 900° F.reactor temperature. The cat/oil ratio was varied between 5 to 8 byvarying the amount of the catalyst. A gas product was collected andanalyzed using a refinery gas analyzer (RGA), equipped with GC with FIDdetector. In-situ regeneration of a spent catalyst was carried out inthe presence of air at 1300° F., and the regeneration flue gas waspassed through a LECO unit to determine the coke yield. A liquid productwas weighted and analyzed in a GC for simulated distillation (D2887) andC₅ ⁻ composition analysis. With a material balance, the yields of coke,dry gas components, LPG components, gasoline (C5-430° F.), light cycleoil (LCO, 430-650° F.) and heavy cycle oil (HCO, 650° F.⁺) weredetermined. The results are summarized below in Table 11.

TABLE 11 Evaluation of Pyrolysis Oil Cofeeding to FCC Feed 20/80 vol20/80 vol % blend, % blend, 100% 100% 100% Sample Sample Sample SampleVGO A/VGO C/VGO A C Cat/Oil, wt/wt 6.0 6.0 6.0 6.0 6.0 Conversion, wt %*81.3 83.15 83.09 76.1 78.82 WLP Impurity** Total O, ppm 81 76 62 54 67Total N, ppm 27 30 33 50 21 Yields Coke, wt % 4.45 4.35 4.20 3.56 2.90Total Dry Gas, wt % 2.08 1.96 1.93 1.55 1.43 Hydrogen 0.16 0.12 0.120.05 0.04 Methane 0.68 0.65 0.64 0.50 0.46 Ethane 0.44 0.43 0.41 0.330.28 Ethylene 0.76 0.74 0.72 0.63 0.61 Total LPG, wt % 21.25 21.08 21.5020.17 24.40 Propane 1.78 1.76 1.72 1.47 1.53 Propylene 5.53 5.51 5.565.57 6.75 n-Butane 1.56 1.56 1.54 1.29 1.34 Isobutane 6.61 6.48 6.645.43 6.61 C4 olefins 5.77 5.77 6.04 6.41 8.16 Gasoline, wt % 53.53 55.7555.46 62.53 61.75 LCO, wt % 12.89 12.23 11.93 10.37 8.03 HCO, wt % 5.814.63 4.98 1.82 1.50 Octane Number*** 88.05 84.57 82.79 73.75 75.41*Conversion - conversion of 430° F.⁺ fraction to 430° F.⁻ **Impuritylevel of N and O in whole liquid product in fuels boiling range by GC ×GC, ppm ***Octane number, (R + M)/2, was estimated from detailedhydrocarbon GC of FCC gasoline.

The results in Table 11 show that up to 20 volume % cofeeding ofpyrolysis oil only makes very slight changes in the FCC unit performanceindicating coprocessing of pyrolysis oil up to 20% is readily feasible.The 20 volume % blending of Sample A or Sample C led to very slightreduction of coke and dry gas yields, slight increase in gasoline yieldand slight decrease in LCO and HCO, which are favorable in mostsituations. With paraffinic nature of pyrolysis oil, the 20% blends of Aand C lowered the Octane number by about 3-5 numbers. With refineryoperational flexibility, these octane number debits can be compensatedwith blending or feeding location adjustments.

The FCC unit cracks the pyrolysis oil info fuel range hydrocarbons,reduces impurities, and isomerize n-paraffins to isoparaffins. All thesechemistry will improve the fuel properties of the pyrolysis oil and wax.By cofeeding the pyrolysis oil through the FCC process unit with azeolite catalyst, the oxygen and nitrogen impurities in the fuel rangewere reduced substantially, from about 300-1400 ppm N to about 30 ppm Nand from about 250-540 ppm O to about 60-80 ppm O. The hydrocarboncomposition of all these cofeeding products are well within the typicalFCC gasoline range.

The FCC runs of 100% pyrolysis oil showed substantial debits of Octanenumbers by about 13-14 numbers. This shows that coprocessing ofpyrolysis oil is preferred over processing of pure 100% pyrolysis oil.

Example 11 Coprocessing of Pyrolysis Wax in a FCC

To study the impact of coprocessing of waste plastics pyrolysis wax in aFCC, a series of laboratory tests were carried out with Sample E andVGO. FCC performances of 20% blend of pyrolysis wax with VGO and purepyrolysis wax were compared with that of the pure VGO feed, similar toExample 10. The results are summarized below in Table 12.

TABLE 12 Evaluation of Pyrolysis Wax Cofeeding to FCC Feed 100% 20/80vol % blend, 100% VGO Sample E/VGO Sample E Cat/Oil, wt/wt 6.5 6.5 6.5Conversion, wt %* 82.75 84.17 91.31 Yields Coke, wt % 4.78 4.76 4.26Total Dry Gas, wt % 2.11 2.05 1.79 Hydrogen 0.16 0.14 0.07 Methane 0.690.67 0.58 Ethane 0.44 0.43 0.37 Ethylene 0.78 0.77 0.73 Total LPG, wt %21.71 23.15 31.79 Propane 1.87 1.93 2.28 Propylene 5.54 5.98 8.59n-Butane 1.65 1.74 2.15 Isobutane 6.91 7.25 8.88 C4 olefins 5.74 6.259.89 Gasoline, wt % 54.16 54.21 53.47 LCO, wt % 12.42 11.59 6.71 HCO, wt% 4.83 4.24 1.99 Octane Number** 89.95 88.38 83.52 *Conversion -conversion of 430° F.⁺ fraction to 430° F.⁻ **Octane number, (R + M)/2,was estimated from detailed hydrocarbon GC of FCC gasoline.

The results in Table 12 shows that up to 20 volume % cofeeding ofpyrolysis wax only makes very slight changes in the FCC unit performanceindicating coprocessing of pyrolysis wax up to 20% is readily feasible.The 20 volume % blending of Sample E led to very slight reduction to nochange of coke and dry gas yields, noticeable increase in LPG olefinyield, very slight increase in gasoline yield and slight decrease in LCOand HCO, which are all favorable in most situations. With paraffinicnature of pyrolysis wax, the 20% blend of Sample E lowered the Octanenumber slightly by 1.5 number. With refinery blending flexibility, thisoctane number debit can be easily compensated with minor blendingadjustments.

The FCC run of 100% pyrolysis wax showed substantial increase inconversion, and debit of the Octane number by 6. This shows thatcoprocessing of pyrolysis wax is preferred over processing of 100%pyrolysis wax.

Example 12 Feeding of Recycled C₃ LPG Stream to Steam Cracker forEthylene Production, Followed by Productions of Polyethylene Resin andPolyethylene Consumer Products

A C₃ LPG stream containing propane and propylene, produced via cofeedingof pyrolysis products to a FCC unit, is separated and fed to a steamcracker for production of ethylene with a recycle content, as shown inFIG. 3 . The ethylene is then processed to a polymerization unit toproduce polyethylene resin containing somerecycled-polyethylene/polypropylene derived materials while the qualityof the newly produced polyethylene is indistinguishable to the virginpolyethylene made entirely from virgin petroleum resources. Thepolyethylene resin with the recycled material is then further processedto produce various polyethylene products to fit the needs of consumerproducts. These polyethylene consumer products now contains chemicallyrecycled, circular polymer while the quality of the polyethyleneconsumer products are indistinguishable from those made entirely fromvirgin polyethylene polymer. These chemically recycled polymer productsare different from the mechanically recycled polymer products whosequalities are inferior to the polymer products made from virginpolymers.

Example 13 Quality Gasoline, Jet and Diesel Product Production withRecycle Content

Cofeeding of pyrolysis oil and/or wax to a FCC unit, as shown inExamples 10 and 11, produces a substantial amount of C₃-C₅ olefins witha recycle content, as well as the gasoline, jet, diesel products. A C₄only or C₄-C₅ stream containing recycled olefins is separated from FCClight-end recovery units, and then fed to an alkylation unit. Reactionof LPG olefins and isobutane in the alkylation reactor produces n-butaneand alkylate gasoline with recycle contents. Alkylate gasoline andn-butane are valuable gasoline blending components. The heavy fractionis further upgraded in a hydrocracking unit to produce quality gasoline,jet and diesel products.

The foregoing examples together clearly showed a new effective way torecycle a large quantity of polyethylene and polypropylene derived wasteplastics via chemical recycling through pyrolysis followed by cofeedingof the pyrolysis products in a refinery via efficient integration. Theexamples also demonstrate the benefits of a filtration/metal oxidetreatment prior to an FCC unit. This integration allows quality fuelsand circular polymer productions.

As used in this disclosure the word “comprises” or “comprising” isintended as an open-ended transition meaning the inclusion of the namedelements, but not necessarily excluding other unnamed elements. Thephrase “consists essentially of” or “consisting essentially of” isintended to mean the exclusion of other elements of any essentialsignificance to the composition. The phrase “consisting of” or “consistsof” is intended as a transition meaning the exclusion of all but therecited elements with the exception of only minor traces of impurities.

All patents and publications referenced herein are hereby incorporatedby reference to the extent not inconsistent herewith. It will beunderstood that certain of the above-described structures, functions,and operations of the above-described embodiments are not necessary topractice the present invention and are included in the descriptionsimply for completeness of an exemplary embodiment or embodiments. Inaddition, it will be understood that specific structures, functions, andoperations set forth in the above-described referenced patents andpublications can be practiced in conjunction with the present invention,but they are not essential to its practice. It is therefore to beunderstood that the invention may be practiced otherwise that asspecifically described without actually departing from the spirit andscope of the present invention as defined by the appended claims.

What is claimed is:
 1. A continuous process for converting waste plasticinto recycle for polyethylene polymerization comprising: (a) selectingwaste plastics containing polyethylene and/or polypropylene; (b) passingthe waste plastics from (a) through a pyrolysis reactor to thermallycrack at least a portion of the polyolefin waste and produce a pyrolyzedeffluent; (c) separating the pyrolyzed effluent into offgas, a pyrolysisoil comprising naphtha, diesel and heavy fractions, and char; (d)passing the pyrolysis oil from (c) to a filtration unit followed by ametal oxide treatment; (e) recovering the treated pyrolysis oil from themetal oxide treatment and passing same to a refinery FCC unit; (f)recovering a liquid petroleum C₃ olefin/paraffin mixture fraction fromthe FCC unit; and (g) passing the liquid petroleum gas C₃olefin/paraffin mixture fraction to a steam cracker for ethyleneproduction.
 2. The process of claim 1, wherein a gasoline and heavyfraction are recovered from the refinery FCC unit.
 3. The process ofclaim 1, wherein ethylene produced in (g) is subsequently polymerized.4. The process of claim 3, wherein polyethylene products are preparedfrom the polymerized ethylene.
 5. The process of claim 2, wherein theamount of gasoline produced by the FCC unit is increased due to thetreated pyrolysis oil passed to the FCC unit in (e).
 6. The process ofclaim 1, wherein the filtration employs a filter having pores averaging5 microns or less in diameter.
 7. The process of claim 6, wherein thepores average less than 1 micron in diameter.
 8. The process of claim 1,wherein the metal oxide treatment comprises a metal oxide selected fromCaO, ZnO, MgO, NiO, MoO₃, alumina, silica, silica-alumina, clay and amixture thereof.
 9. The process of claim 1, wherein the metal oxidetreatment occurs at a temperature above 200° F. (93° C.).
 10. Theprocess of claim 1, wherein the waste plastics selected in (a) are fromplastics classification group 2, 4, and/or
 5. 11. The process of claim1, wherein the filtration/metal oxide treatment occurs in a refinerycomprising the FCC unit.
 12. The process of claim 1, wherein filtrationoccurs at a pyrolysis facility and the metal oxide treatment occurs at arefinery comprising the FCC unit.
 13. The process of claim 1, whereinthe content of heptane insolubles is reduced to less than 0.1 wt % afterthe filtration treatment.
 14. The process of claim 1, wherein thechloride content is reduced to less 5 ppm after the metal oxidetreatment.
 15. The process of claim 1, wherein the total metal impuritycontent is less than 10 ppm after the metal oxide treatment.
 16. Theprocess of claim 1, wherein solid particulate and chloride reduction isachieved in the filtration/metal oxide treatment of (d), and S, diene,olefin, and N reduction is achieved by the refinery FCC unit.
 17. Theprocess of claim 1, wherein the filtration unit employs a filter havingpores averaging 5 microns or less in diameter, and the metal oxidetreatment comprises a metal oxide selected from CaO, ZnO, MgO, NiO,MoO₃, alumina, silica, silica-alumina, clay or a mixture thereof.
 18. Acontinuous process for converting waste plastic into recycle forpolyethylene polymerization comprising: (a) selecting waste plasticscontaining polyethylene and/or polypropylene; (b) passing the wasteplastics from (a) through a pyrolysis reactor to thermally crack atleast a portion of the polyolefin waste and produce a pyrolyzedeffluent; (c) separating the pyrolyzed effluent into offgas, a pyrolysisoil comprising a naphtha/diesel/heavy fraction, and char; (d) passingthe pyrolysis oil from (c) to a filtration unit followed by a metaloxide treatment; (e) recovering the treated pyrolysis oil from the metaloxide treatment and passing same to a refinery FCC feed pretreatmentunit; (f) recovering effluent from the FCC feed pretreatment unit andpassing the effluent to a FCC unit; (g) recovering a liquid petroleum C₃olefin/paraffin mixture fraction from the FCC unit; and (h) passing theliquid petroleum gas C₃ olefin/paraffin mixture fraction to a steamcracker for ethylene production.
 19. The process of claim 18, wherein agasoline and heavy fraction is recovered from the refinery FCC unit. 20.The process of claim 18, wherein the waste plastics selected in (a) arefrom plastics classification group 2, 4, and/or
 5. 21. The process ofclaim 19, wherein the amount of gasoline produced by the FCC unit isincreased due to the treated pyrolysis oil passed to the FCC unit in(e).
 22. The process of claim 18, wherein ethylene produced in (h) issubsequently polymerized.
 23. The process of claim 22, whereinpolyethylene products are prepared from the polymerized ethylene. 24.The process of claim 18, wherein the filtration employs a filter havingpores averaging 5 microns or less in diameter.
 25. The process of claim24, wherein the pores average less than 1 micron in diameter.
 26. Theprocess of claim 18, wherein the metal oxide treatment comprises a metaloxide selected from CaO, ZnO, MgO, NiO, MoO₃, alumina, silica,silica-alumina, clay, and a mixture thereof.
 27. The process of claim18, wherein the metal oxide treatment occurs at a temperature above 200°F. (93° C.).
 28. The process of claim 18, wherein the content of heptaneinsolubles is reduced to less than 0.1 wt. % after the filtrationtreatment.
 29. The process of claim 18, wherein the chloride content isreduced to less 5 ppm after the metal oxide treatment.
 30. The processof claim 18, wherein the total impurity metal content is less than 10ppm after the metal oxide treatment.
 31. The process of claim 18,wherein solid particulates and chloride reduction is achieved in thefiltration/metal oxide treatment of (d), and S, diene, olefin and Nreduction is achieved in the FCC feed pretreatment unit.
 32. The processof claim 18, wherein only filtration occurs at a pyrolysis facility andthe metal oxide treatment occurs at a refinery comprising the FCC unit.33. The process of claim 18, wherein the filtration unit employs afilter having pores averaging 5 microns or less in diameter, and themetal oxide treatment comprises a metal oxide selected from CaO, ZnO,MgO, NiO, MoO₃, alumina, silica, silica-alumina, clay or a mixturethereof.
 34. A continuous process for converting waste plastic intorecycle for polyethylene polymerization comprising: (a) selecting wasteplastics containing polyethylene and/or polypropylene; (b) passing thewaste plastics from (a) through a pyrolysis reactor to thermally crackat least a portion of the polyolefin waste and produce a pyrolyzedeffluent; (c) separating the pyrolyzed effluent into offgas, a pyrolysisoil comprising naphtha, diesel and heavy fractions, and char; (d)passing the pyrolysis oil from (c) to a filtration unit followed by ametal oxide treatment; and (e) recovering the treated pyrolysis oil fromthe metal oxide treatment and forwarding same to a refinery forpreparation of ethylene.
 35. The process of claim 34, wherein thefiltration employs a filter having pores averaging 5 microns or less indiameter.
 36. The process of claim 34, wherein the pores average lessthan 1 micron in diameter.
 37. The process of claim 34, wherein themetal oxide treatment comprises a metal oxide selected from CaO, ZnO,MgO, alumina, silica, silica-alumina, and a mixture thereof.
 38. Theprocess of claim 34, wherein the metal oxide treatment occurs at atemperature above 200° F. (93° C.).
 39. The process of claim 34, whereinthe content of heptane insolubles is reduced to less than 0.1 wt % afterthe filtration treatment.
 40. The process of claim 34, wherein thechloride content is reduced to less 5 ppm after the metal oxidetreatment.
 41. The process of claim 34, wherein the total metal impuritycontent is less than 10 ppm after the metal oxide treatment.
 42. Theprocess of claim 34, wherein filtration occurs at a pyrolysis facilityand the metal oxide treatment occurs at a refinery comprising a FCCunit.
 43. The process of claim 34, wherein the waste plastics selectedin (a) are from plastics classification group 2, 4, and/or
 5. 44. Theprocess of claim 34 further comprising producing a fuel product in therefinery and blending the product to produce gasoline, jet and/or dieselproducts.
 45. The process of claim 43, wherein a jet fuel product isproduced.
 46. The process of claim 44, wherein gasoline is produced inthe refinery.
 47. The process of claim 44, wherein diesel fuel isproduced in the refinery.
 48. The process of claim 34, wherein thefiltration unit employs a filter having pores averaging 5 microns orless in diameter, and the metal oxide treatment comprises a metal oxideselected from CaO, ZnO, MgO, NiO, MoO₃, alumina, silica, silica-alumina,clay or a mixture thereof.
 49. A continuous process for converting wasteplastic into recycle for polyethylene polymerization comprising: (a)selecting waste plastics containing polyethylene and/or polypropylene;(b) passing the waste plastics from (a) through a pyrolysis reactor tothermally crack at least a portion of the polyolefin waste and produce apyrolyzed effluent; (c) separating the pyrolyzed effluent into offgas, apyrolysis oil comprising naphtha, diesel and heavy fractions, and char;(d) passing the diesel and heavy fractions of the pyrolysis oil, or theheavy fraction of the pyrolysis oil from (c) to a filtration unitfollowed by a metal oxide treatment; (e) recovering the treatedpyrolysis oil from the metal oxide treatment and passing same to arefinery FCC unit; (f) recovering a liquid petroleum C₃ olefin/paraffinmixture fraction from the FCC unit; and (g) passing the liquid petroleumgas C₃ olefin/paraffin mixture fraction to a steam cracker for ethyleneproduction.